The following is the summary of “Time from symptom onset may influence C-reactive protein utility in the diagnosis of bacterial infections in the NICU” published in the December 2022 issue of Pediatrics by Borowski, et al.
C-reactive protein (CRP) testing may function better in identifying bacterial infections in the neonatal intensive care unit (NICU) if the time of the test is considered. In this study, researchers looked at how the yield of CRP changed as time progressed from the onset of symptoms. Patients were enrolled if they were being treated in the NICU and had a CRP drawn as part of a sepsis workup. A record was kept of when symptoms started and when blood was taken. According to the standards set forth by the National Healthcare Safety Network (NHSN), patients were divided into two categories: those with and without bacterial infections.
Receiver-operating characteristic (ROC) curve analysis was used to compare the effectiveness of CRP, CRP velocity, and CRP collected before or after 6 hours from the beginning of symptoms. Bayesian formulas were used to determine test characteristics. A total of 21 (or 16%) of the 129 newborns enrolled in the trial were infected with germs. Area under the receiver operating characteristic curve was 0.75 (95% CI: 0.61-0.89) for a single CRP test and 0.77 (95% CI:0.66-0.88) for CRP velocity when determining the presence of bacterial infection. For CRP tests taken within 6 hours of symptom onset, a cutoff value of 1 mg/dL is recommended, while for those taken less than 6 hours later, a cutoff value of 1.5 mg/dL is recommended.
The probability ranged from 35% to 38% after using the appropriate cut-off settings, up from 16% before the test. CRP has a low diagnostic accuracy for babies born weighing less than 1000 g. Diagnosing bacterial infections in NICU patients using the appropriate CRP cut-off varies with time from symptom onset. When blood cultures continue to be negative for bacteria and other germs, a “negative” CRP may lend credence to the decision to discontinue empiric antimicrobial treatment.